The first infant was born on at home in a tub filled with tap water. A different midwife delivered the second baby at home in a rented Jacuzzi hot tub, instead of a disposable birthing tub.

"Investigation of these two cases identified numerous gaps in infection prevention for water births, including use of a jetted Jacuzzi rather than a disposable birthing tub, and allowing the water to remain for a week at 98 degrees … which is within the optimum range for Legionella growth," according to the Centers for Disease Control and Prevention.

Tap water is not sterile and Legionella can grow and spread in man-made water systems, the report said.